Asana is another spray that controls the balsam woolly adelgid, a European insect that has devastated Fraser firs in forest stands, flattening their tops, swelling their joints and hardening their wood.

Hemlock trees more than four centuries old still live on steep slopes from Alabama to Maine, although they are now facing destruction by the hemlock woolly adelgid, a pest introduced from Asia forty years ago.

Over the past thirty years, these unique forests have been decimated by the balsam woolly adelgid, an aphid-like insect introduced from Europe.